gepic93

Does anyone know if there are still problems with the AX series bearings? I'm going to get an engine for a future plane on Christmas and was planning on going with an AX until I heard about this problem. What size engine is most practical for Christmas when I don't know what plane I'm getting? I want to get some kind of seaplane/floatplane and was thinging a .55 or something.

da Rock

Jeez, what bearing problem?

We've got a ton of 'em flying around here. Three clubs of over 50-60 members each and almost 2/3s the members have at least one. And haven't heard of anyone having a bearing problem.

Ed_Moorman

My Feedback: (1)

I have 4 .46AXs, well 3 and pieces, a twin took a bad hit on one side, and a .55. Never had any problem. I do run Omega, castor blend fuel, 10% nitro. I run slightly rich so I start off with a small smoke trail. I rarely, if ever, use after engine run oil.

The only bearings I ever had trouble with were in an MVVS .40. All right, I replaced some Saito .72 breaings, but it was on a seaplane and got dunked in salt water. You should have seen the throttle servo.

gepic93

well I've been hearing a lot about some bearing problem in AX in these forums they could just be the old ones

The Toolman

Are you sure that isn't the older FX's?


Ronnie

moto-x

I have ran my 46 ax for 2 seasons hard on omega fuel. I would guees about 10 gallons of fuel. I am on my 3rd plug just for the hell of it. None have burnt out. I fell its the best two stroke out there right now. Just my opinion.

w8ye

My Feedback: (16)

I've been around a lot of different AX's and I've never seen one with a bearing problem.

NorfolkSouthern

One day while out at the field, a guy had a Tower trainer. Him and his instructor (an engine guru, I might add) spent all day trying to get it to run properly. The instructor finally gave in and recommended a new engine. The student returned the next day, with a brand new 46 AX with the Powerbox muffler (I bought one just like it later) installed on his model. They just ran it through a tank for run-in, and flew the rest of the day without even a missfire. That student has never had trouble starting since: One or two flips and he was up up while I kept cranking my old K&B 40. Nobody I know at the club has had a problem with the bearings on an OS AX series, I've never heard anything bad about them.

NorfolkSouthern

w8ye

My Feedback: (16)

Bearing problems are more often than not caused by rust.

The rust comes from moisture and/or acids for by the combustion process of the methanol based fuels.

While I've replaced a lot of glow engine bearings, I never seen a gasoline model engine with any rust inside.

da Rock

I'm all over these forums and really haven't seen any posts that mention bearing problems with those engines. Also, I got a number of 46AXs, a couple of 55AXs, and just now got a 75AX. And have had a couple apart. The bearings are very high quality for your average model engine, but that's not surprising, OS is a very high quality mfg.

BTW, I sold my 1st 46AX to a guy who flew it all this year. He can't set a needle worth spit. And won't bother most times. And wound up loading the sucker down something awful one day for two flights that trashed the piston and head (melted the faces of both). When he rebuilt it, he commented on how excellent the bearings looked and put it down to the fuel I use. He switched to that fuel. The castor in the fuel might have done something for the bearings, but I put it down to good bearings AND good fuel. He had to rebuild one of his about the same time he rebuilt the one he bought from me. His had seen a year of his all-synthetic fuel. It's bearings looked like the hinges on a barn door, and were why he was rebuilding that one. Even the best finished steel will rust, no fault of the steel.

So, nah, there isn't a problem, and anyone who you hear saying there is needs to go onto your "take with a grain of salt" list.

blw

My Feedback: (3)

OS has had some batches of bad bearings in the past according to reports here on RCU. All of the engine manufacturers probably contract out for them. I think the bad ones were during the FX period, but this is all normal for glow engines. Plus, one can never tell when a bearing issue is due to neglect.

daven

My Feedback: (1)

The bearing issue was with the .46 AX, very soon after they came out. We went to the motor for our local racing class, so we saw alot of them. Quite a few people had issues with the bearings rusting virtually overnight. The bearings in the motor now appear different looking than the original cheap Chinease bearings that were initially in the motor. I'm in belief that it was a bad batch, since we haven't seen the problem on these motors after that first summer. Some of us went to ceramic bearings with stainless races, I can't remember the site, but they were reasonable (under $30), others went with the Swiss Made bearings from www.pspec.com , and many just use the stock bearings.

I don't think its an issue that would dissuade me from buying more of these motors, they are very nice and powerfull motors for their size.

mdomokos

I came searching for a thread about OS AX bearing issues because my OS 75AX, which I have had for 5 months with about 30 flights on it, just had a bearing failure today. I am sending it back hoping for it to be covered under warranty. So........I guess I am the only one with an AX bearing failure?

liquid_TR

Any bearing can fail at any time - no matter which brand or type.

OS usually uses a NTN brand (Japan) bearing on the front, and a NSK brand (Japan) bearing on the back. - Same as Saito, Magnum, and several others.

Its a basic two stroke design - the bearing is flushed with fresh fuel while the engine is running. So either your rear bearing had a fault from the bearing mfg - which has nothing to do with OS

or

you had your fair share of unbalanced prop running and/or lean runs and/or low quality synthetic oil in fuel which led to a bearing failure.

DarZeelon

Mdomokos,


Whenever I say OS use bearings that are of lesser quality in their engines, I am labeled as an "OS basher"...

If only OS used good bearings...
In some other engines, bearings could last the life of an engine.

The rear bearing in your OS is a 35x17x8 16003 bearing, which for some reason Tower calls an 18003...

The front one is a single shield 24x12x5.5 mm 6901Z.

You can get [link=http://www.rc-bearings.com/catalog/product_info.php?cPath=81_87_98&products_id=671&osCsid=a027f9f302c304441f0c908749fcf33e]a new standard set from RC-Bearings[/link], for less than $8, or [link=http://www.rc-bearings.com/catalog/product_info.php?cPath=111_116_125&products_id=831&osCsid=a027f9f302c304441f0c908749fcf33e]the hybrid ceramic set[/link] for $29, with $5 for the stainless races option.

Don't bother looking elsewhere, since all you will see is higher prices for the same stuff...

mdomokos

My intent is to send it back for warranty service. I don't know if OS will cover it. I think they should. I used Model Masters 15% fuel or Byron 15% at all times. I used Hobbico's after run oil most times I wasn 't going to fly for 2 weeks. I balance my props, not sure about the lean runs, I always make sure I am trailing smoke. Is is worth paying for the stainless race option? Will they last longer?

DarZeelon

Mdomokos,


Stainless bearing steel is not completely rust-proof.

Its resistance to rust, however, is much greater than that of normal bearing steel.
The bearings will remain corrosion-free under all but the worst abuse.

They will, however, wear somewhat faster, since this stainless steel is softer than [link=http://www.precisionballs.com/TDS/Bearing_Steel.htm]52100 bearing steel[/link].

Bearing steel is 60 Rockwell C and stainless bearing steel is typically 58 Rockwell C.

Since rust will typically make a bearing unusable faster than does wear, my opinion is that it is preferable to opt for the stainless steel races.